Perhaps you should try some spelling variations:
representations based » presentation based, representation basic, representational basis
commercial crisis » commercial crimes, commercial risks, commercial credits
based studies » case studies
modes shared » model shared, mode share, des shared
modal shares » modal share

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: commercial crisis ((modes shared) OR (modal shares)) representations based studies.~.
• Adding a wildcard symbol may retrieve word variants: commercial crisis ((modes shared) or (modal shares)) representations based studies.*.